My experience is actually quite different. Woolies often has the more lucrative offers (e.g. earn 6000 points by spending $30 in week 1, $40 in week 2 and $50 in week 3 meanwhile all the Coles offers for a couple thousand points expect me to spend over a hundred for several weeks). I will agree that Woolies is easier to chase down for points although FlyBuys does have an email address you can use if you just want to jot off a quick message about missing points and aren't in a rush for points to appear in your account. In terms of Coles vs Woolies, Coles tends to have a better selection of ready made food (e.g. "fresh" pizzas and Youfoodz selection). However, for me the clincher is the free home delivery from Woolies which I get since I'm in a high risk group.
-RooFlyer88